BMX icon Dave Mirra, who died of a self-inflicted gunshot wound in February, was suffering from a type of brain damage seen in former football and hockey players, according to a new report from ESPN The Magazine.

The 41-year-old, a freestyle BMX superstar who won 24 medals in X Games competition, is the first action sports athlete to be diagnosed with chronic traumatic encephalopathy, or CTE. The degenerative disease can lead to depression, dementia and memory loss, and after Mirra took his own life on February 4, his family decided to have his brain studied by a neuropathologist at the University of Toronto.

Dr. Lili-Naz Hazrati, who performed the tests on Mirra’s brain, told ESPN that it showed protein deposits commonly found in the brains of athletes who had suffered repeated head trauma – “I couldn’t tell the difference,” she said. “It’s assumed it is related to multiple concussions that happened years before.” Hazrati also sent images of prepared slides (without Mirra’s name or background information) to fellow neuropathologists in the U.S. and Canada, each of whom confirmed her diagnosis of CTE.

Related

“It validates what we have been thinking about brain injuries in boxers and football players,” Hazrati said. “The key is brain injury. Regardless of how you get it, through BMX or hockey, you are at risk for this.”

Mirra suffered a fractured skull after being hit by a car at age 19, and endured an unknown number of concussions during his BMX career. He also dabbled in boxing and rallycross racing after retiring from riding.

Mirra’s widow, Lauren, told ESPN that she had begun to notice changes in her husband’s behavior last summer, and added that he was also dealing with “fatigue, both physically and emotionally…forgetfulness [and] moodiness.”

“I remember seeing him sitting on our bed one day, in the last month of his life. I had just gotten out of the shower and saw him hunched over with the blankest, lost look,” she said. “I sat down next to him and held his hand. I said, ‘What is wrong? Are you OK?’ And he just shrugged his shoulders. He couldn’t even speak. He didn’t know. He couldn’t put it into words. He was lost. He was helpless. It was completely different from who he was.”

Lauren Mirra said that, while she knew something was wrong with her husband, he was unaware of CTE “until his last week or two,” after friends convinced him to watch the Will Smith film Concussion. And his death served as a grim reminder of just how serious the issue of brain trauma truly is.

“My biggest takeaway is that [suicide] is something Dave would never, ever, in his right mind, have chosen,” she said. “He was sick. And this is real. This is a real disease.”